Active immunity comes from your own immune system responding to the Hep B vaccine — it’s slow to build but lasts for decades. Passive immunity comes from an injection of ready antibodies (HBIG) — it works instantly but fades in months. Both can be lifesaving when timed right: • Vaccine = long-term shield • HBIG = emergency umbrella Together, they protect healthcare workers, newborns, and anyone exposed to Hepatitis B For post-exposure: HBIG + vaccine = best of both worlds — immediate + lasting immunity.